SEACI taps into future water availability

Australia’s water resources can be better managed under a changing climate, thanks to research released last week by the South Eastern Australian Climate Initiative (SEACI).

The SEACI Phase 2 Synthesis Report ‘Climate and water availability in south-eastern Australia’, launched at the initiative’s annual workshop in Canberra, addresses key science questions behind the causes of climate variability and change, and their impacts on water availability across the Murray-Darling Basin, Victoria and southern South Australia.

SEACI research provides evidence that there appear to be long-term reductions occurring in cool season rainfall across south-eastern Australia, and that these changes are at least partly attributed to climate change.

“The cool season is the traditional ‘filling season’ for water supply systems across most of south-eastern Australia, and SEACI research reveals this important cool season rainfall may be less reliable into the future,” SEACI Program Director David Post said.

“SEACI research shows the reduction in cool season rainfall is caused by an expansion of tropical influences, driven by the Hadley Circulation expanding at a rate of 0.5° of latitude (approximately 50 km) per decade, pushing mid-latitude storm tracks further south and leading to reduced cool season rainfall across southern Australia.

“Our modelling shows this observed expansion of the Hadley Circulation can only be reproduced if human influences (such as greenhouse gases, aerosols and stratospheric ozone) are included in the models. This provides evidence that observed changes in large-scale atmospheric circulation patterns affecting south-eastern Australia are at least partly attributable to climate change.”

Climate projections indicate that these changes are likely to continue into the future.

“If the southern section of the SEACI region (south of Sydney) experienced a 1°C warming, the average annual rainfall is expected to decline by between 0 and 9% and average annual runoff by between 2 and 22%. These reductions could double with a 2°C warming,” Dr Post said.

“Climate projections show a range of possible impacts, and water resource managers need to ensure that their planning and management processes are robust and can adapt to a wide range of future climate and streamflow scenarios.”

SEACI also contributed to improvements in the seasonal forecasting of rainfall and streamflow across south-eastern Australia, with forecasts available online at www.bom.gov.au/water/ssf. These improved forecasts will assist resource managers and users in adapting to a variable climate.

The second phase of SEACI (2009-2012) was a $9 million partnership between CSIRO, the Bureau of Meteorology, the Murray-Darling Basin Authority, the Victorian Department of Sustainability and Environment and the Australian Government Department of Climate Change and Energy Efficiency.